The purpose of this study is to evaluate the diagnostic accuracy of thoracicmagnetic resonance imaging with gadolinium-enhanced, unenhanced and perfusion sequences in patients with clinically suspected acute pulmonary embolism

Thoracic CT angiography (CTA) will serve as reference standard

Result of MRI will not interfere with patients' management

Untreated patients with negative CTA will have 3-month follow-up to verify they were free of thrombose-embolic disease

Further study details as provided by Assistance Publique - Hôpitaux de Paris:

Primary Outcome Measures:

MRI studies will be interpreted at the end of the inclusion process. CTA results will serve as reference standard to evaluate MRI sensitivity, specificity, positive and negative predictive values. Inter-observer agreement will be evaluated [ Time Frame: 17 months after the first inclusion ] [ Designated as safety issue: No ]

Secondary Outcome Measures:

3 months clinical follow-up will be performed in patients with negative CTA results who did not receive anticoagulation. This is to verify there were no false negatives on CTA [ Time Frame: 3 months afer CTA ] [ Designated as safety issue: No ]

Background In patients with clinically suspected pulmonary embolism (PE)°with a contraindication to thoracic CT angiography, there is a need for an alternative diagnostic procedure. MRI has not been fully evaluated in this field; moreover, recent technological advances make it necessary to re-evaluate its performance for PE diagnosis.

A non-inclusion register will be establish for patients fulfilling the inclusion criteria , not included because MRI was not available (off-hours presentation , another patients already included in the protocol on the same day )

Magnetic Resonance imaging: performed on a 1.5 Tesla unit with 3 different sequences

Unenhanced Steady State Free Precession (SSFP) sequences

Perfusion imaging following Gadolinium injection at a rate of 5 c/s and a dose of 0.1mmol/kg

Magnetic resonance angiography following an injection of 0.1mmol/kg of gadolinium at 3ml/s MRI studies will be interpreted secondarily by 2 independent radiologists, blinded to CTA results and clinical probability.

Two different readings will be performed, one global reading and one reading of each sequence separately, displayed in a random order (access base)

Objectives

to evaluate MRI performance for PE diagnosis globally

to evaluate the diagnostic value for each sequence (especially the negative predictive value of a normal perfusion sequence)

Allergy to gadolinium-containing contrast agent or to iodinated contrast media

Renal insufficiency (clearance less than 30 ml/mn)

Anticoagulation at a curative dose started more than 48 hours prior to MRI

Life expectancy less than 3 months

Pregnancy

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01077778